Dogfight? Dachshund fans described the findings as 'rubbish', but detractors called them 'yappy little things'

Next in the list of 33 breeds was an even smaller dog, the Chihuahua, followed by Jack Russell terriers.

The highest-rated large dog was the Akita, at number four, while the pit bull came sixth. Rottweilers and Rhodesian ridgebacks didn't even make it into the top ten.

The study, published in the journal Applied Animal Behaviour Science, was based on interviews with 6,000 dog owners by researchers at the University of Pennsylvania.

One of the researchers, Dr James Serpell, said the findings suggested smaller breeds were more genetically predisposed towards aggressive behaviour. Previous research into the area has generally been based on dog bite statistics.

But bites from larger dogs are more likely to need medical attention and the researchers said this might have skewed results as most attacks were not being reported.

According to their study, the pit bull, rottweiler and Rhodesian ridgeback rated average or below average for hostility towards strangers. Golden retrievers, basset hounds, labradors, Siberian huskies and greyhounds came low on the list for aggression.

Chris Moore, of the Northern Dachshund Association, described the findings as 'rubbish'. He said: 'It is not in the dogs' nature. I have never been bitten in 25 years.'

Pam Bungard, of the British Chihuahua Club, said she had owned 14 and come into contact with hundreds of others over the past quarter of a century.

'I judge the breed and I have never been bitten by one. They are a bit yappy but soon they are sitting on people and jumping all over them. I think people could be confusing excitement with aggression.'

The Rottweiler Club in Britain agreed with the researchers' findings, however. Treasurer Joyce Summers said: 'I have lived with Rottweilers for 40 years and they give nothing but love and affection. I am not surprised Jack Russells are up there near the top. They are yappy little things.'

Canine behaviour consultant Jacquie Bunn said: 'Aggressive behaviour is much more prevalent in small dogs than large and it's something behaviourists and trainers have known for some years.'